Corfe Castle [Hardy's Corvsgate Castle ]. Source of photograph: The Hand of Ethelberta in the Anniversary Edition of the Wessex Novels, 1920, facing p. 260. Scanned image (2002) by Philip V. Allingham; text by Allingham and George P. Landow. [You may use this image without prior permission for any scholarly or educational purpose as long as you (1) credit the person who scanned the image and (2) link your document to this URL.]

According to the editors, many of whose remarks seem based on Thomas Hardy's Wessex (1913) by Herman Lea,

Corvsgate Castle is the counterfeit presentment of Corfe Castle, the
ruins of which are situated near Swanage. This ancient castle, after
many vicissitudes, was blown up at the time of the [Puritan]
Commonwealth, and has since remained in ruins. "In the windy corridors"
and "mildewed dungeons" of this castle Peter the Hermit, Edward II,
and KIng John were once prisoners.

References

Hardy, Thomas. The Hand of Ethelberta. "Anniversary Edition of the Wessex Novels." New York & London: Harper & Brothers, 1920. This edition derives in
part from previous editions and the photographs of 1912.